The present invention generally relates to replaceable batteries for electric road vehicles (i.e., traction batteries), and more particularly, to a system for facilitating the connection of such batteries to a charging device either located at a replacement station (i.e., for "re-fueling") or otherwise operated by the owner of the vehicle.
Despite their undisputed ecological advantages, electric road vehicles still have the significant shortcoming that the batteries for such vehicles require a large storage capacity, even for relatively short excursions. To provide the vehicle with a useful radius of operation, a significant number of very heavy batteries must necessarily be employed.
The use of such vehicles can be made practical with exchangeable batteries, and the construction of battery replacement stations where the spent batteries of a vehicle may be exchanged for charged batteries (on a carry-out basis). To be of practical value, such a battery exchange must occur both quickly and easily. Special techniques are required for this.
One such consideration is that a suitable replacement device is needed for removing the traction battery (either removed battery in storage (for purposes of recharging and maintenance), and for taking a fresh battery (or batteries) from storage, for insertion into the electric vehicle. Since significant weights are involved, and depending on the type of vehicle, different replacement devices often had to be developed for different applications. As an example, compare electric buses and electric transports. For electric buses, battery replenishment is carried out by charging and maintaining the batteries, as a unit. For electric transports, battery replenishment is carried out by moving a service cart between the transport and a fixed charging/maintenance position.
A replacement station for electric road vehicles equipped with exchangeable batteries is disclosed in German (Utility Model) No. DE-Gbm 93 05 542. The disclosed replacement station employs a commercial enclosure having an interior which is divided into a battery room containing a battery replacement device and a room containing a battery charger. The commercial enclosure takes the form of a modular container which is easily transported from one location to the next. An important component of this battery replacement device is a roller belt equipped with telescoping arms which, after opening a roller gate on the container housing, can be unfolded (outwardly) to make a connection with the vehicle. The roller belt is connectable with a roller belt provided in the electric road vehicle, which receives a battery tray. The telescoping arms include appropriate rigging for equalizing small differences in distance between the respective roller belts.
The battery replacement device employs a lifting table, which can be moved along rails in the battery room. The battery is in this way moved to a storage (or charging) position. In this position, the lifting table (with its side facing away from the vehicle) is connected to one of the battery storage racks that occupy the rear of the battery room. The storage racks also have roller belts that are placed in motion during docking of the lifting table.
Following docking of the lifting table, the operator (e.g., the bus driver) then connects a charging plug to a socket associated with the battery, initiating the charging process (as well as automatic water refilling or other service functions, as required). Each charging position has optical displays for indicating the state of the battery charging procedure, including an indication of fully charged, or damaged batteries. The charging position is controlled responsive to corresponding controls and readouts.
When ready for use, the fully charged battery is removed from the battery charger, and from the replacement station. All of the functional procedures involved in removal of the charged battery are the same as the procedures involved in introducing the discharged battery to the replacement station. Only the sequence of operations, and the direction of rotation of the roller belts, is reversed.
Electrical connection between the electrical system of the vehicle, including its motor, and the battery is made with a plug-in coupling. Coupling plugs that can be used in the previously mentioned replacement stations are described, for example, in DE-Gbm 90 03 174 and DE-Gbm 91 14 909.
DE-Gbm 90 03 174 discloses a device for connecting a traction battery (with electrolyte circulation) to a power supply and a compressed gas (electrolyte) source. The device includes an air coupling and an electrical coupling having plug parts and socket parts which are mechanically joined. Both parts can be coupled with the simultaneous production of a pneumatic connection and an electrical connection.
DE-Gbm 91 14 909 discloses a connecting device which includes a plug part (an electrical coupling) which is mechanically connected to a plug part for connection to a water supply and a plug part for connection to an air line, for simultaneously connecting the storage battery to different supply devices (i.e., a battery charger and a source of compressed gas for an electrolyte circulating pump). A mated socket corresponds to the connection plug.
In both instances, a base plate permits the plug and socket parts to be adapted to a combined air/water coupling and a corresponding standard electrical connection. All of the connections can be integrated in a common housing, for the plug part or for the socket part.
However, the plug connections required for the previously mentioned replacement station (for bus batteries), for the orderly charging of such batteries (including charging current, air for acid circulation, water for refilling the cells, water for heating or cooling the batteries, and optional auxiliary contacts), are made by hand. As part of this, the hand plugs must be removed from the fully charged battery (which is to be installed in the vehicle), and then plugged into the used battery removed from the vehicle. On the one hand, such a manual process is subject to the possibility of error. On the other hand, such a manual process tends to introduce delays into the battery replacement process. Moreover, moving through the (extremely crowded) replacement station to manually plug and unplug the necessary connections can soil the user's clothing. As an example, this would be true for uniformed bus drivers who must carry out the battery replacement process during a brief pause in driving.